Configurable keys 2 (Mapping keys to commands) (#268)

* Add convenience/clarity wrapper for Range initialization

* Add keycode parse and display methods

* Add remapping functions and tests

* Implement key remapping

* Add remapping book entry

* Use raw string literal for toml

* Add command constants

* Make command functions private

* Map directly to commands

* Match key parsing/displaying to Kakoune

* Formatting pass

* Update documentation

* Formatting

* Fix example in the book

* Refactor into single config file

* Formatting

* Refactor configuration and add keymap newtype wrappers

* Address first batch of PR comments

* Replace FromStr with custom deserialize

book/src/SUMMARY.md

@@ -4,4 +4,5 @@ # Summary
 - [Usage](./usage.md)
 - [Configuration](./configuration.md)
   - [Keymap](./keymap.md)
+  - [Key Remapping](./remapping.md)
   - [Hooks](./hooks.md)

book/src/remapping.md

@@ -0,0 +1,48 @@
+# Key Remapping
+
+One-way key remapping is temporarily supported via a simple TOML configuration
+file. (More powerful solutions such as rebinding via commands will be
+available in the feature).
+
+To remap keys, write a `config.toml` file in your `helix` configuration
+directory (default `~/.config/helix` in Linux systems) with a structure like
+this:
+
+```toml
+# At most one section each of 'keys.normal', 'keys.insert' and 'keys.select'
+[keys.normal]
+a = "move_char_left" # Maps the 'a' key to the move_char_left command
+w = "move_line_up" # Maps the 'w' key move_line_up
+C-S-esc = "select_line" # Maps Control-Shift-Escape to select_line
+
+[keys.insert]
+A-x = "normal_mode" # Maps Alt-X to enter normal mode
+```
+
+Control, Shift and Alt modifiers are encoded respectively with the prefixes
+`C-`, `S-` and `A-`. Special keys are encoded as follows:
+
+* Backspace => "backspace"
+* Space => "space"
+* Return/Enter => "ret"
+* < => "lt"
+* > => "gt"
+* + => "plus"
+* - => "minus"
+* ; => "semicolon"
+* % => "percent"
+* Left => "left"
+* Right => "right"
+* Up => "up"
+* Home => "home"
+* End => "end"
+* Page Up => "pageup"
+* Page Down => "pagedown"
+* Tab => "tab"
+* Back Tab => "backtab"
+* Delete => "del"
+* Insert => "ins"
+* Null => "null"
+* Escape => "esc"
+
+Commands can be found in the source code at `../../helix-term/src/commands.rs`

helix-term/src/application.rs

@@ -1,7 +1,7 @@
 use helix_lsp::lsp;
 use helix_view::{document::Mode, Document, Editor, Theme, View};
 
-use crate::{args::Args, compositor::Compositor, ui};
+use crate::{args::Args, compositor::Compositor, config::Config, keymap::Keymaps, ui};
 
 use log::{error, info};
 
@@ -40,13 +40,14 @@ pub struct Application {
 }
 
 impl Application {
-    pub fn new(mut args: Args) -> Result<Self, Error> {
+    pub fn new(mut args: Args, config: Config) -> Result<Self, Error> {
         use helix_view::editor::Action;
         let mut compositor = Compositor::new()?;
         let size = compositor.size();
         let mut editor = Editor::new(size);
 
-        compositor.push(Box::new(ui::EditorView::new()));
+        let mut editor_view = Box::new(ui::EditorView::new(config.keymaps));
+        compositor.push(editor_view);
 
         if !args.files.is_empty() {
             let first = &args.files[0]; // we know it's not empty

helix-term/src/config.rs

@@ -0,0 +1,33 @@
+use anyhow::{Error, Result};
+use std::{collections::HashMap, str::FromStr};
+
+use serde::{de::Error as SerdeError, Deserialize, Serialize};
+
+use crate::keymap::{parse_keymaps, Keymaps};
+
+#[derive(Default)]
+pub struct Config {
+    pub keymaps: Keymaps,
+}
+
+#[derive(Serialize, Deserialize)]
+struct TomlConfig {
+    keys: Option<HashMap<String, HashMap<String, String>>>,
+}
+
+impl<'de> Deserialize<'de> for Config {
+    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
+    where
+        D: serde::Deserializer<'de>,
+    {
+        let config = TomlConfig::deserialize(deserializer)?;
+        Ok(Self {
+            keymaps: config
+                .keys
+                .map(|r| parse_keymaps(&r))
+                .transpose()
+                .map_err(|e| D::Error::custom(format!("Error deserializing keymap: {}", e)))?
+                .unwrap_or_else(Keymaps::default),
+        })
+    }
+}

helix-term/src/keymap.rs

@@ -1,7 +1,14 @@
-use crate::commands::{self, Command};
+use crate::commands;
+pub use crate::commands::Command;
+use anyhow::{anyhow, Error, Result};
 use helix_core::hashmap;
 use helix_view::document::Mode;
-use std::collections::HashMap;
+use std::{
+    collections::HashMap,
+    fmt::Display,
+    ops::{Deref, DerefMut},
+    str::FromStr,
+};
 
 // Kakoune-inspired:
 // mode = {
@@ -95,8 +102,10 @@
 // #[cfg(feature = "term")]
 pub use crossterm::event::{KeyCode, KeyEvent, KeyModifiers};
 
-pub type Keymap = HashMap<KeyEvent, Command>;
-pub type Keymaps = HashMap<Mode, Keymap>;
+#[derive(Clone, Debug)]
+pub struct Keymap(pub HashMap<KeyEvent, Command>);
+#[derive(Clone, Debug)]
+pub struct Keymaps(pub HashMap<Mode, Keymap>);
 
 #[macro_export]
 macro_rules! key {
@@ -132,188 +141,491 @@ macro_rules! alt {
     };
 }
 
-pub fn default() -> Keymaps {
-    let normal = hashmap!(
-        key!('h') => commands::move_char_left as Command,
-        key!('j') => commands::move_line_down,
-        key!('k') => commands::move_line_up,
-        key!('l') => commands::move_char_right,
+impl Default for Keymaps {
+    fn default() -> Self {
+        let normal = Keymap(hashmap!(
+            key!('h') => Command::move_char_left,
+            key!('j') => Command::move_line_down,
+            key!('k') => Command::move_line_up,
+            key!('l') => Command::move_char_right,
 
-        key!(Left) => commands::move_char_left,
-        key!(Down) => commands::move_line_down,
-        key!(Up) => commands::move_line_up,
-        key!(Right) => commands::move_char_right,
+            key!(Left) => Command::move_char_left,
+            key!(Down) => Command::move_line_down,
+            key!(Up) => Command::move_line_up,
+            key!(Right) => Command::move_char_right,
 
-        key!('t') => commands::find_till_char,
-        key!('f') => commands::find_next_char,
-        key!('T') => commands::till_prev_char,
-        key!('F') => commands::find_prev_char,
-        // and matching set for select mode (extend)
-        //
-        key!('r') => commands::replace,
-        key!('R') => commands::replace_with_yanked,
+            key!('t') => Command::find_till_char,
+            key!('f') => Command::find_next_char,
+            key!('T') => Command::till_prev_char,
+            key!('F') => Command::find_prev_char,
+            // and matching set for select mode (extend)
+            //
+            key!('r') => Command::replace,
+            key!('R') => Command::replace_with_yanked,
 
-        key!(Home) => commands::move_line_start,
-        key!(End) => commands::move_line_end,
+            key!(Home) => Command::move_line_start,
+            key!(End) => Command::move_line_end,
 
-        key!('w') => commands::move_next_word_start,
-        key!('b') => commands::move_prev_word_start,
-        key!('e') => commands::move_next_word_end,
+            key!('w') => Command::move_next_word_start,
+            key!('b') => Command::move_prev_word_start,
+            key!('e') => Command::move_next_word_end,
 
-        key!('v') => commands::select_mode,
-        key!('g') => commands::goto_mode,
-        key!(':') => commands::command_mode,
+            key!('v') => Command::select_mode,
+            key!('g') => Command::goto_mode,
+            key!(':') => Command::command_mode,
 
-        key!('i') => commands::insert_mode,
-        key!('I') => commands::prepend_to_line,
-        key!('a') => commands::append_mode,
-        key!('A') => commands::append_to_line,
-        key!('o') => commands::open_below,
-        key!('O') => commands::open_above,
-        // [<space>  ]<space> equivalents too (add blank new line, no edit)
+            key!('i') => Command::insert_mode,
+            key!('I') => Command::prepend_to_line,
+            key!('a') => Command::append_mode,
+            key!('A') => Command::append_to_line,
+            key!('o') => Command::open_below,
+            key!('O') => Command::open_above,
+            // [<space>  ]<space> equivalents too (add blank new line, no edit)
 
 
-        key!('d') => commands::delete_selection,
-        // TODO: also delete without yanking
-        key!('c') => commands::change_selection,
-        // TODO: also change delete without yanking
+            key!('d') => Command::delete_selection,
+            // TODO: also delete without yanking
+            key!('c') => Command::change_selection,
+            // TODO: also change delete without yanking
 
-        // key!('r') => commands::replace_with_char,
+            // key!('r') => Command::replace_with_char,
 
-        key!('s') => commands::select_regex,
-        alt!('s') => commands::split_selection_on_newline,
-        key!('S') => commands::split_selection,
-        key!(';') => commands::collapse_selection,
-        alt!(';') => commands::flip_selections,
-        key!('%') => commands::select_all,
-        key!('x') => commands::select_line,
-        key!('X') => commands::extend_line,
-        // or select mode X?
-        // extend_to_whole_line, crop_to_whole_line
+            key!('s') => Command::select_regex,
+            alt!('s') => Command::split_selection_on_newline,
+            key!('S') => Command::split_selection,
+            key!(';') => Command::collapse_selection,
+            alt!(';') => Command::flip_selections,
+            key!('%') => Command::select_all,
+            key!('x') => Command::select_line,
+            key!('X') => Command::extend_line,
+            // or select mode X?
+            // extend_to_whole_line, crop_to_whole_line
 
 
-        key!('m') => commands::match_brackets,
-        // TODO: refactor into
-        // key!('m') => commands::select_to_matching,
-        // key!('M') => commands::back_select_to_matching,
-        // select mode extend equivalents
+            key!('m') => Command::match_brackets,
+            // TODO: refactor into
+            // key!('m') => commands::select_to_matching,
+            // key!('M') => commands::back_select_to_matching,
+            // select mode extend equivalents
 
-        // key!('.') => commands::repeat_insert,
-        // repeat_select
+            // key!('.') => commands::repeat_insert,
+            // repeat_select
 
-        // TODO: figure out what key to use
-        // key!('[') => commands::expand_selection, ??
-        key!('[') => commands::left_bracket_mode,
-        key!(']') => commands::right_bracket_mode,
+            // TODO: figure out what key to use
+            // key!('[') => Command::expand_selection, ??
+            key!('[') => Command::left_bracket_mode,
+            key!(']') => Command::right_bracket_mode,
 
-        key!('/') => commands::search,
-        // ? for search_reverse
-        key!('n') => commands::search_next,
-        key!('N') => commands::extend_search_next,
-        // N for search_prev
-        key!('*') => commands::search_selection,
+            key!('/') => Command::search,
+            // ? for search_reverse
+            key!('n') => Command::search_next,
+            key!('N') => Command::extend_search_next,
+            // N for search_prev
+            key!('*') => Command::search_selection,
 
-        key!('u') => commands::undo,
-        key!('U') => commands::redo,
+            key!('u') => Command::undo,
+            key!('U') => Command::redo,
 
-        key!('y') => commands::yank,
-        // yank_all
-        key!('p') => commands::paste_after,
-        // paste_all
-        key!('P') => commands::paste_before,
+            key!('y') => Command::yank,
+            // yank_all
+            key!('p') => Command::paste_after,
+            // paste_all
+            key!('P') => Command::paste_before,
 
-        key!('>') => commands::indent,
-        key!('<') => commands::unindent,
-        key!('=') => commands::format_selections,
-        key!('J') => commands::join_selections,
-        // TODO: conflicts hover/doc
-        key!('K') => commands::keep_selections,
-        // TODO: and another method for inverse
+            key!('>') => Command::indent,
+            key!('<') => Command::unindent,
+            key!('=') => Command::format_selections,
+            key!('J') => Command::join_selections,
+            // TODO: conflicts hover/doc
+            key!('K') => Command::keep_selections,
+            // TODO: and another method for inverse
 
-        // TODO: clashes with space mode
-        key!(' ') => commands::keep_primary_selection,
+            // TODO: clashes with space mode
+            key!(' ') => Command::keep_primary_selection,
 
-        // key!('q') => commands::record_macro,
-        // key!('Q') => commands::replay_macro,
+            // key!('q') => Command::record_macro,
+            // key!('Q') => Command::replay_macro,
 
-        // ~ / apostrophe => change case
-        // & align selections
-        // _ trim selections
+            // ~ / apostrophe => change case
+            // & align selections
+            // _ trim selections
 
-        // C / altC = copy (repeat) selections on prev/next lines
+            // C / altC = copy (repeat) selections on prev/next lines
 
-        key!(Esc) => commands::normal_mode,
-        key!(PageUp) => commands::page_up,
-        key!(PageDown) => commands::page_down,
-        ctrl!('b') => commands::page_up,
-        ctrl!('f') => commands::page_down,
-        ctrl!('u') => commands::half_page_up,
-        ctrl!('d') => commands::half_page_down,
+            key!(Esc) => Command::normal_mode,
+            key!(PageUp) => Command::page_up,
+            key!(PageDown) => Command::page_down,
+            ctrl!('b') => Command::page_up,
+            ctrl!('f') => Command::page_down,
+            ctrl!('u') => Command::half_page_up,
+            ctrl!('d') => Command::half_page_down,
 
-        ctrl!('w') => commands::window_mode,
+            ctrl!('w') => Command::window_mode,
 
-        // move under <space>c
-        ctrl!('c') => commands::toggle_comments,
-        key!('K') => commands::hover,
+            // move under <space>c
+            ctrl!('c') => Command::toggle_comments,
+            key!('K') => Command::hover,
 
-        // z family for save/restore/combine from/to sels from register
+            // z family for save/restore/combine from/to sels from register
 
-        // supposedly ctrl!('i') but did not work
-        key!(Tab) => commands::jump_forward,
-        ctrl!('o') => commands::jump_backward,
-        // ctrl!('s') => commands::save_selection,
+            // supposedly ctrl!('i') but did not work
+            key!(Tab) => Command::jump_forward,
+            ctrl!('o') => Command::jump_backward,
+            // ctrl!('s') => Command::save_selection,
 
-        key!(' ') => commands::space_mode,
-        key!('z') => commands::view_mode,
+            key!(' ') => Command::space_mode,
+            key!('z') => Command::view_mode,
 
-        key!('"') => commands::select_register,
-    );
-    // TODO: decide whether we want normal mode to also be select mode (kakoune-like), or whether
-    // we keep this separate select mode. More keys can fit into normal mode then, but it's weird
-    // because some selection operations can now be done from normal mode, some from select mode.
-    let mut select = normal.clone();
-    select.extend(
-        hashmap!(
-            key!('h') => commands::extend_char_left as Command,
-            key!('j') => commands::extend_line_down,
-            key!('k') => commands::extend_line_up,
-            key!('l') => commands::extend_char_right,
+            key!('"') => Command::select_register,
+        ));
+        // TODO: decide whether we want normal mode to also be select mode (kakoune-like), or whether
+        // we keep this separate select mode. More keys can fit into normal mode then, but it's weird
+        // because some selection operations can now be done from normal mode, some from select mode.
+        let mut select = normal.clone();
+        select.0.extend(
+            hashmap!(
+                key!('h') => Command::extend_char_left,
+                key!('j') => Command::extend_line_down,
+                key!('k') => Command::extend_line_up,
+                key!('l') => Command::extend_char_right,
 
-            key!(Left) => commands::extend_char_left,
-            key!(Down) => commands::extend_line_down,
-            key!(Up) => commands::extend_line_up,
-            key!(Right) => commands::extend_char_right,
+                key!(Left) => Command::extend_char_left,
+                key!(Down) => Command::extend_line_down,
+                key!(Up) => Command::extend_line_up,
+                key!(Right) => Command::extend_char_right,
 
-            key!('w') => commands::extend_next_word_start,
-            key!('b') => commands::extend_prev_word_start,
-            key!('e') => commands::extend_next_word_end,
+                key!('w') => Command::extend_next_word_start,
+                key!('b') => Command::extend_prev_word_start,
+                key!('e') => Command::extend_next_word_end,
 
-            key!('t') => commands::extend_till_char,
-            key!('f') => commands::extend_next_char,
+                key!('t') => Command::extend_till_char,
+                key!('f') => Command::extend_next_char,
 
-            key!('T') => commands::extend_till_prev_char,
-            key!('F') => commands::extend_prev_char,
-            key!(Home) => commands::extend_line_start,
-            key!(End) => commands::extend_line_end,
-            key!(Esc) => commands::exit_select_mode,
-        )
-        .into_iter(),
-    );
+                key!('T') => Command::extend_till_prev_char,
+                key!('F') => Command::extend_prev_char,
+                key!(Home) => Command::extend_line_start,
+                key!(End) => Command::extend_line_end,
+                key!(Esc) => Command::exit_select_mode,
+            )
+            .into_iter(),
+        );
 
-    hashmap!(
-        // as long as you cast the first item, rust is able to infer the other cases
-        // TODO: select could be normal mode with some bindings merged over
-        Mode::Normal => normal,
-        Mode::Select => select,
-        Mode::Insert => hashmap!(
-            key!(Esc) => commands::normal_mode as Command,
-            key!(Backspace) => commands::insert::delete_char_backward,
-            key!(Delete) => commands::insert::delete_char_forward,
-            key!(Enter) => commands::insert::insert_newline,
-            key!(Tab) => commands::insert::insert_tab,
-
-            ctrl!('x') => commands::completion,
-            ctrl!('w') => commands::insert::delete_word_backward,
-        ),
-    )
+        Keymaps(hashmap!(
+            // as long as you cast the first item, rust is able to infer the other cases
+            // TODO: select could be normal mode with some bindings merged over
+            Mode::Normal => normal,
+            Mode::Select => select,
+            Mode::Insert => Keymap(hashmap!(
+                key!(Esc) => Command::normal_mode as Command,
+                key!(Backspace) => Command::delete_char_backward,
+                key!(Delete) => Command::delete_char_forward,
+                key!(Enter) => Command::insert_newline,
+                key!(Tab) => Command::insert_tab,
+                ctrl!('x') => Command::completion,
+                ctrl!('w') => Command::delete_word_backward,
+            )),
+        ))
+    }
+}
+
+// Newtype wrapper over keys to allow toml serialization/parsing
+#[derive(Debug, PartialEq, PartialOrd, Clone, Copy, Hash)]
+pub struct RepresentableKeyEvent(pub KeyEvent);
+impl Display for RepresentableKeyEvent {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        let Self(key) = self;
+        f.write_fmt(format_args!(
+            "{}{}{}",
+            if key.modifiers.contains(KeyModifiers::SHIFT) {
+                "S-"
+            } else {
+                ""
+            },
+            if key.modifiers.contains(KeyModifiers::ALT) {
+                "A-"
+            } else {
+                ""
+            },
+            if key.modifiers.contains(KeyModifiers::CONTROL) {
+                "C-"
+            } else {
+                ""
+            },
+        ))?;
+        match key.code {
+            KeyCode::Backspace => f.write_str("backspace")?,
+            KeyCode::Enter => f.write_str("ret")?,
+            KeyCode::Left => f.write_str("left")?,
+            KeyCode::Right => f.write_str("right")?,
+            KeyCode::Up => f.write_str("up")?,
+            KeyCode::Down => f.write_str("down")?,
+            KeyCode::Home => f.write_str("home")?,
+            KeyCode::End => f.write_str("end")?,
+            KeyCode::PageUp => f.write_str("pageup")?,
+            KeyCode::PageDown => f.write_str("pagedown")?,
+            KeyCode::Tab => f.write_str("tab")?,
+            KeyCode::BackTab => f.write_str("backtab")?,
+            KeyCode::Delete => f.write_str("del")?,
+            KeyCode::Insert => f.write_str("ins")?,
+            KeyCode::Null => f.write_str("null")?,
+            KeyCode::Esc => f.write_str("esc")?,
+            KeyCode::Char('<') => f.write_str("lt")?,
+            KeyCode::Char('>') => f.write_str("gt")?,
+            KeyCode::Char('+') => f.write_str("plus")?,
+            KeyCode::Char('-') => f.write_str("minus")?,
+            KeyCode::Char(';') => f.write_str("semicolon")?,
+            KeyCode::Char('%') => f.write_str("percent")?,
+            KeyCode::F(i) => f.write_fmt(format_args!("F{}", i))?,
+            KeyCode::Char(c) => f.write_fmt(format_args!("{}", c))?,
+        };
+        Ok(())
+    }
+}
+
+impl FromStr for RepresentableKeyEvent {
+    type Err = Error;
+
+    fn from_str(s: &str) -> Result<Self, Self::Err> {
+        let mut tokens: Vec<_> = s.split('-').collect();
+        let code = match tokens.pop().ok_or_else(|| anyhow!("Missing key code"))? {
+            "backspace" => KeyCode::Backspace,
+            "space" => KeyCode::Char(' '),
+            "ret" => KeyCode::Enter,
+            "lt" => KeyCode::Char('<'),
+            "gt" => KeyCode::Char('>'),
+            "plus" => KeyCode::Char('+'),
+            "minus" => KeyCode::Char('-'),
+            "semicolon" => KeyCode::Char(';'),
+            "percent" => KeyCode::Char('%'),
+            "left" => KeyCode::Left,
+            "right" => KeyCode::Right,
+            "up" => KeyCode::Down,
+            "home" => KeyCode::Home,
+            "end" => KeyCode::End,
+            "pageup" => KeyCode::PageUp,
+            "pagedown" => KeyCode::PageDown,
+            "tab" => KeyCode::Tab,
+            "backtab" => KeyCode::BackTab,
+            "del" => KeyCode::Delete,
+            "ins" => KeyCode::Insert,
+            "null" => KeyCode::Null,
+            "esc" => KeyCode::Esc,
+            single if single.len() == 1 => KeyCode::Char(single.chars().next().unwrap()),
+            function if function.len() > 1 && function.starts_with('F') => {
+                let function: String = function.chars().skip(1).collect();
+                let function = str::parse::<u8>(&function)?;
+                (function > 0 && function < 13)
+                    .then(|| KeyCode::F(function))
+                    .ok_or_else(|| anyhow!("Invalid function key '{}'", function))?
+            }
+            invalid => return Err(anyhow!("Invalid key code '{}'", invalid)),
+        };
+
+        let mut modifiers = KeyModifiers::empty();
+        for token in tokens {
+            let flag = match token {
+                "S" => KeyModifiers::SHIFT,
+                "A" => KeyModifiers::ALT,
+                "C" => KeyModifiers::CONTROL,
+                _ => return Err(anyhow!("Invalid key modifier '{}-'", token)),
+            };
+
+            if modifiers.contains(flag) {
+                return Err(anyhow!("Repeated key modifier '{}-'", token));
+            }
+            modifiers.insert(flag);
+        }
+
+        Ok(RepresentableKeyEvent(KeyEvent { code, modifiers }))
+    }
+}
+
+pub fn parse_keymaps(toml_keymaps: &HashMap<String, HashMap<String, String>>) -> Result<Keymaps> {
+    let mut keymaps = Keymaps::default();
+
+    for (mode, map) in toml_keymaps {
+        let mode = Mode::from_str(&mode)?;
+        for (key, command) in map {
+            let key = str::parse::<RepresentableKeyEvent>(&key)?;
+            let command = str::parse::<Command>(&command)?;
+            keymaps.0.get_mut(&mode).unwrap().0.insert(key.0, command);
+        }
+    }
+    Ok(keymaps)
+}
+
+impl Deref for Keymap {
+    type Target = HashMap<KeyEvent, Command>;
+    fn deref(&self) -> &Self::Target {
+        &self.0
+    }
+}
+
+impl Deref for Keymaps {
+    type Target = HashMap<Mode, Keymap>;
+    fn deref(&self) -> &Self::Target {
+        &self.0
+    }
+}
+
+impl DerefMut for Keymap {
+    fn deref_mut(&mut self) -> &mut Self::Target {
+        &mut self.0
+    }
+}
+
+impl DerefMut for Keymaps {
+    fn deref_mut(&mut self) -> &mut Self::Target {
+        &mut self.0
+    }
+}
+
+#[cfg(test)]
+mod test {
+    use crate::config::Config;
+
+    use super::*;
+
+    impl PartialEq for Command {
+        fn eq(&self, other: &Self) -> bool {
+            self.name() == other.name()
+        }
+    }
+
+    #[test]
+    fn parsing_keymaps_config_file() {
+        let sample_keymaps = r#"
+            [keys.insert]
+            y = "move_line_down"
+            S-C-a = "delete_selection"
+
+            [keys.normal]
+            A-F12 = "move_next_word_end"
+        "#;
+
+        let config: Config = toml::from_str(sample_keymaps).unwrap();
+        assert_eq!(
+            *config
+                .keymaps
+                .0
+                .get(&Mode::Insert)
+                .unwrap()
+                .0
+                .get(&KeyEvent {
+                    code: KeyCode::Char('y'),
+                    modifiers: KeyModifiers::NONE
+                })
+                .unwrap(),
+            Command::move_line_down
+        );
+        assert_eq!(
+            *config
+                .keymaps
+                .0
+                .get(&Mode::Insert)
+                .unwrap()
+                .0
+                .get(&KeyEvent {
+                    code: KeyCode::Char('a'),
+                    modifiers: KeyModifiers::SHIFT | KeyModifiers::CONTROL
+                })
+                .unwrap(),
+            Command::delete_selection
+        );
+        assert_eq!(
+            *config
+                .keymaps
+                .0
+                .get(&Mode::Normal)
+                .unwrap()
+                .0
+                .get(&KeyEvent {
+                    code: KeyCode::F(12),
+                    modifiers: KeyModifiers::ALT
+                })
+                .unwrap(),
+            Command::move_next_word_end
+        );
+    }
+
+    #[test]
+    fn parsing_unmodified_keys() {
+        assert_eq!(
+            str::parse::<RepresentableKeyEvent>("backspace").unwrap(),
+            RepresentableKeyEvent(KeyEvent {
+                code: KeyCode::Backspace,
+                modifiers: KeyModifiers::NONE
+            })
+        );
+
+        assert_eq!(
+            str::parse::<RepresentableKeyEvent>("left").unwrap(),
+            RepresentableKeyEvent(KeyEvent {
+                code: KeyCode::Left,
+                modifiers: KeyModifiers::NONE
+            })
+        );
+
+        assert_eq!(
+            str::parse::<RepresentableKeyEvent>(",").unwrap(),
+            RepresentableKeyEvent(KeyEvent {
+                code: KeyCode::Char(','),
+                modifiers: KeyModifiers::NONE
+            })
+        );
+
+        assert_eq!(
+            str::parse::<RepresentableKeyEvent>("w").unwrap(),
+            RepresentableKeyEvent(KeyEvent {
+                code: KeyCode::Char('w'),
+                modifiers: KeyModifiers::NONE
+            })
+        );
+
+        assert_eq!(
+            str::parse::<RepresentableKeyEvent>("F12").unwrap(),
+            RepresentableKeyEvent(KeyEvent {
+                code: KeyCode::F(12),
+                modifiers: KeyModifiers::NONE
+            })
+        );
+    }
+
+    fn parsing_modified_keys() {
+        assert_eq!(
+            str::parse::<RepresentableKeyEvent>("S-minus").unwrap(),
+            RepresentableKeyEvent(KeyEvent {
+                code: KeyCode::Char('-'),
+                modifiers: KeyModifiers::SHIFT
+            })
+        );
+
+        assert_eq!(
+            str::parse::<RepresentableKeyEvent>("C-A-S-F12").unwrap(),
+            RepresentableKeyEvent(KeyEvent {
+                code: KeyCode::F(12),
+                modifiers: KeyModifiers::SHIFT | KeyModifiers::CONTROL | KeyModifiers::ALT
+            })
+        );
+
+        assert_eq!(
+            str::parse::<RepresentableKeyEvent>("S-C-2").unwrap(),
+            RepresentableKeyEvent(KeyEvent {
+                code: KeyCode::F(2),
+                modifiers: KeyModifiers::SHIFT | KeyModifiers::CONTROL
+            })
+        );
+    }
+
+    #[test]
+    fn parsing_nonsensical_keys_fails() {
+        assert!(str::parse::<RepresentableKeyEvent>("F13").is_err());
+        assert!(str::parse::<RepresentableKeyEvent>("F0").is_err());
+        assert!(str::parse::<RepresentableKeyEvent>("aaa").is_err());
+        assert!(str::parse::<RepresentableKeyEvent>("S-S-a").is_err());
+        assert!(str::parse::<RepresentableKeyEvent>("C-A-S-C-1").is_err());
+        assert!(str::parse::<RepresentableKeyEvent>("FU").is_err());
+        assert!(str::parse::<RepresentableKeyEvent>("123").is_err());
+        assert!(str::parse::<RepresentableKeyEvent>("S--").is_err());
+    }
 }

helix-term/src/lib.rs

@@ -4,5 +4,6 @@
 pub mod args;
 pub mod commands;
 pub mod compositor;
+pub mod config;
 pub mod keymap;
 pub mod ui;

helix-term/src/main.rs

@@ -1,6 +1,6 @@
 use helix_term::application::Application;
 use helix_term::args::Args;
-
+use helix_term::config::Config;
 use std::path::PathBuf;
 
 use anyhow::{Context, Result};
@@ -89,10 +89,17 @@ async fn main() -> Result<()> {
         std::fs::create_dir_all(&conf_dir).ok();
     }
 
+    let config = std::fs::read_to_string(conf_dir.join("config.toml"))
+        .ok()
+        .map(|s| toml::from_str(&s))
+        .transpose()?
+        .or_else(|| Some(Config::default()))
+        .unwrap();
+
     setup_logging(logpath, args.verbosity).context("failed to initialize logging")?;
 
     // TODO: use the thread local executor to spawn the application task separately from the work pool
-    let mut app = Application::new(args).context("unable to create new appliction")?;
+    let mut app = Application::new(args, config).context("unable to create new application")?;
     app.run().await.unwrap();
 
     Ok(())

helix-term/src/ui/editor.rs

@@ -11,10 +11,7 @@
     syntax::{self, HighlightEvent},
     Position, Range,
 };
-use helix_view::{
-    document::{IndentStyle, Mode},
-    Document, Editor, Theme, View,
-};
+use helix_view::{document::Mode, Document, Editor, Theme, View};
 use std::borrow::Cow;
 
 use crossterm::{
@@ -30,7 +27,7 @@
 };
 
 pub struct EditorView {
-    keymap: Keymaps,
+    keymaps: Keymaps,
     on_next_key: Option<Box<dyn FnOnce(&mut commands::Context, KeyEvent)>>,
     last_insert: (commands::Command, Vec<KeyEvent>),
     completion: Option<Completion>,
@@ -40,16 +37,16 @@ pub struct EditorView {
 
 impl Default for EditorView {
     fn default() -> Self {
-        Self::new()
+        Self::new(Keymaps::default())
     }
 }
 
 impl EditorView {
-    pub fn new() -> Self {
+    pub fn new(keymaps: Keymaps) -> Self {
         Self {
-            keymap: keymap::default(),
+            keymaps,
             on_next_key: None,
-            last_insert: (commands::normal_mode, Vec::new()),
+            last_insert: (commands::Command::normal_mode, Vec::new()),
             completion: None,
         }
     }
@@ -546,8 +543,8 @@ pub fn render_statusline(
     }
 
     fn insert_mode(&self, cx: &mut commands::Context, event: KeyEvent) {
-        if let Some(command) = self.keymap[&Mode::Insert].get(&event) {
-            command(cx);
+        if let Some(command) = self.keymaps[&Mode::Insert].get(&event) {
+            command.execute(cx);
         } else if let KeyEvent {
             code: KeyCode::Char(ch),
             ..
@@ -568,7 +565,7 @@ fn command_mode(&self, mode: Mode, cxt: &mut commands::Context, event: KeyEvent)
             // special handling for repeat operator
             key!('.') => {
                 // first execute whatever put us into insert mode
-                (self.last_insert.0)(cxt);
+                self.last_insert.0.execute(cxt);
                 // then replay the inputs
                 for key in &self.last_insert.1 {
                     self.insert_mode(cxt, *key)
@@ -584,8 +581,8 @@ fn command_mode(&self, mode: Mode, cxt: &mut commands::Context, event: KeyEvent)
                 // set the register
                 cxt.selected_register = cxt.editor.selected_register.take();
 
-                if let Some(command) = self.keymap[&mode].get(&event) {
-                    command(cxt);
+                if let Some(command) = self.keymaps[&mode].get(&event) {
+                    command.execute(cxt);
                 }
             }
         }
@@ -699,7 +696,7 @@ fn handle_event(&mut self, event: Event, cx: &mut Context) -> EventResult {
                         // how we entered insert mode is important, and we should track that so
                         // we can repeat the side effect.
 
-                        self.last_insert.0 = self.keymap[&mode][&key];
+                        self.last_insert.0 = self.keymaps[&mode][&key];
                         self.last_insert.1.clear();
                     }
                     (Mode::Insert, Mode::Normal) => {

helix-view/src/document.rs

@@ -1,7 +1,9 @@
-use anyhow::{Context, Error};
+use anyhow::{anyhow, Context, Error};
 use std::cell::Cell;
+use std::fmt::Display;
 use std::future::Future;
 use std::path::{Component, Path, PathBuf};
+use std::str::FromStr;
 use std::sync::Arc;
 
 use helix_core::{
@@ -86,6 +88,29 @@ fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
     }
 }
 
+impl Display for Mode {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        match self {
+            Mode::Normal => f.write_str("normal"),
+            Mode::Select => f.write_str("select"),
+            Mode::Insert => f.write_str("insert"),
+        }
+    }
+}
+
+impl FromStr for Mode {
+    type Err = Error;
+
+    fn from_str(s: &str) -> Result<Self, Self::Err> {
+        match s {
+            "normal" => Ok(Mode::Normal),
+            "select" => Ok(Mode::Select),
+            "insert" => Ok(Mode::Insert),
+            _ => Err(anyhow!("Invalid mode '{}'", s)),
+        }
+    }
+}
+
 /// Like std::mem::replace() except it allows the replacement value to be mapped from the
 /// original value.
 fn take_with<T, F>(mut_ref: &mut T, closure: F)